All organomercury compounds are neurotoxic, and the lipid-soluble and bio-accumulative methylmercury (MeHg) is the most dangerous and would pose potential threats to human health and even had caused Minamata disease in Japan in 1960s. High MeHg levels have frequently been reported in remote areas where are rarely affected by human activities. Wetlands have been widely recognized as principal zones of MeHg production in estuarine, boreal ponds, and arctic regions.
The Qinghai-Tibetan Plateau (QTP), known as the “Water Tower of Asia” and one the most remote regions in the world, has exhibited unexpected Hg pollution recently. However, few information is available on how MeHg is produced in wetlands along the Yarlung Tsangbo River (YTR), which is the largest river flowing from west to east through the southern part of Tibet.
A research led by Dr. ZHANG Zhongsheng, from the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, found unexpected high MeHg contents in wetland soils along the YTR recently. Total mercury (THg) and MeHg contents were 62.9 ng/g and 5.88 ng/g, respectively. About 12.6% of total Hg was in the form of MeHg.
This is the first report on high MeHg contents in wetlands along the YTR. “Most mercury here is input by plant biomass, and MeHg production is closely related to phytoplankton”, said Dr. ZHANG. High MeHg contents in wetland soils could bring potential ecological risks to the health of the residents and wild animals along the YTR, and this is worthy to be investigated in the future.
This study has been published in the journal Geoderma entitled with "Unexpected high methylmercury contents related to soil organic carbon and its molecular composition in wetland soils of the Yarlung Tsangbo River, Tibet".
The research was supported by the National Key Research and Developement Program of China, National Natural Science Foundation of China, and the Youth Innovation Promotion Association, CAS.
ZHANG Zhongsheng
Northeast Institute of Geography and Agroecology, CAS
E-mail: zzslycn@iga.ac.cn
